Vaisala refractometers use the critical angle measurement principle. A refractometer's three essential components are a light source, a prism, and an image detector.
The light source sends rays to the prism and process interface at different angles. Rays with a steep angle partly reflect at the image detector and partially refract at the process. Low-angle rays reflect entirely on the detector. The angle from which the total reflection starts is called the critical angle.
The CCD camera detects a bright and dark field corresponding to partly reflected and totally reflected light. The position of the borderline between the bright and the dark area correlates with the critical angle, which is a function of the refractive index and correlates with the solution's concentration.
A built-in temperature sensor measures the temperature T on the interface of the process liquid. The sensor converts the refractive index nD and temperature T into concentration units.
Vaisala K-PATENTS refractometer can indicate different scales, for example, Brix, liquid density, or concentration by weight. The diagnostics program ensures that the measurement is reliable.
Miller Energy, Inc.
800-631-5454
